This invention relates to a steam peeling or cooking apparatus for produce, such as potatoes, carrots, celeriac, red beets, Swedish turnips, apples, and the like, comprising a substantially cylindrical peeling vessel basically stationary in operation, said vessel including supply and discharge conduits for medium, in particular steam, and having closable supply and discharge openings, and being divided into two compartments by a grid-like screen arranged substantially at right angles to the axis of the peeling vessel, the compartment not being in direct contact with the produce supply opening forming a condensate chamber and including a closable discharge opening, said apparatus further including means for agitating the produce during operation.
In similar apparatus described in Dutch patent applications Nos. 76,11025 and 78,112678, the produce is loaded and unloaded by way of a closable top opening. Steam is supplied and discharged by means of trunnions by which the peeling vessel is suspended in a tiltable manner.
In such an apparatus, the total cycle time is determined on the one hand by the actual steaming time of the produce (this is a produce-dependent time) and on the other hand by a produce-independent time (sometimes referred to as the dead time), being the time needed for filling, emptying, valve movement, steam blow-off, tilting and the like.
The produce-dependent time is a fixed datum, so when a shorter cycle time is desired, it should be tried to shorten the produce-independent time: it should be borne in mind that the total cycle time is as short as about 60 seconds and consists as to at most half of produce-dependent time.
Major drawbacks of the prior art apparatus are: the tilting required for filling and emptying the peeling vessel necessitates a drive mechanism with bearing etc. Since a peeling vessel of several tons is concerned here, a heavy drive mechanism with fittings is necessary, by means of which fittings steam can be supplied and discharged. In order to avoid unduly expensive bearings, rotary stuffing box etc., the diameter of the steam supply and discharge line traversing the bearings should be limited. This implies that steam blow-off cannot take place in an optimal i.e. explosive manner. Yet this is desirable in order to ensure that the peel is released and blown off already during steam blow-off. Moreover, explosive or rapid steam blow-off will also ensure that the temperature in the vessel falls rapidly, which reduces the permeation of heat into the product and results in a minimum thickness of the so-called cook ring. By cook ring is understood that portion of fruit or vegetable which has been in contact with steam. This softer portion will be partly removed with the peel and if too thick will result in undue product losses and waste water contamination. The longer the produce is in contact with steam, the greater will be the depth of steam penetration and hence the cook ring thickness. It will be clear, therefore, that after the actual steaming time required for peel removal, the steam is to be discharged as quickly as possible in order to minimize the cook ring thickness.